1. Field
The present invention relates to a thermal swing carbon dioxide recovery concentration apparatus which collects carbon dioxide by a high recovery rate and condenses the carbon dioxide to high concentration with little consumption energy.
2. Description of the Related Art
The effort and trail to reduce carbon dioxide emitted from industry, a car and a home as much as possible as counterplan against global warming is carried out on the world level. For example, the apparatus which consumes energy is improved to become an energy saving type and the old apparatus is replaced by the improved apparatus. As apparatus which produces energies such as power generation, etc., some technologies using renewable energy such as sunlight and wind force, a thermal power plant is improved to raise the power generation efficiency and a technology of recovery concentration of the carbon dioxide emitted from a thermal power plant to store in underground or deep sea in the future is developed and researched.
In the above efforts and trials, especially the present invention relates to the technology for collecting and condensing carbon dioxide from the gas discharged from a thermal power plant, a combustion furnace, etc.
As the thermal power plant, some types of the plants use oil, natural gas and coal for fuel has spread most, and in addition to this, other types burn the garbage discharged from a city. The thermal power plant which uses coal as fuel has the following feature. That is, the electric power is supplied in a stabilized state since the coal is not expensive, there are many global deposits of coal farther than oil and a burying place is also in every corner of the earth so that the coal is easy to obtain.
However, the coal has a problem that the coal emits a carbon dioxide and a sulfide much at the time of combustion of the coal as compared with oil or natural gas. Not only coal but also heavy oil has the same problem as the coal has. For this reason, in the plant which uses coal and heavy crude oil as fuel, the device from which SOx and nitrogen oxide are removed is provided to prevent from environmental pollution.
However, even if SOx and nitrogen oxide were removed and it prevented environmental pollution, carbon dioxide was still emitted so much and there remains a problem of promoting global warming.
As an improvement plan, research and development in the technology of carrying out separation recovery concentration of the carbon dioxide in exhaust gas and storing the collected carbon dioxide in underground or deep sea is making progress. The separation recovery concentrating method of this carbon dioxide is proposed variously, for example, deep freeze method, absorbing method, adsorption method, film separation method, etc.
The deep freeze method is the method of pressurizing material gas and carrying out liquefaction separation of the carbon dioxide utilizing the difference of the liquefaction temperature of each gas under pressurization. In this method, the electric power of the compressor which compresses gas and the electric power of the freezer which carries out deep freeze are required. For example, if carbon dioxide levels are just over or below 10%, the remaining gas which does not need to be collected other than carbon dioxide and which is 90% also comes to be compressed and frozen simultaneously. Therefore, energy expenditure becomes excessive.
The absorbing method is the method of recovering by absorbing carbon dioxide by alkaline fluid such as an amine system, desorbing the carbon dioxide by heating and condensing the carbon dioxide. The method is already put to practical use. However, an expensive corrosion-resistant material is required for dealing with alkaline fluid, and it costs high. Although the heat exchanger was used for the key devices and energy saving of a whole system has been attained, since the calorific capacity of the fluid to be used is large, the limit of the energy saving is approached. (Non-patent literature 2) Furthermore, there is a problem of the secondary contamination since the medicine to be vaporized is used.
The adsorption method uses gas adsorption material such as zeolite and activated carbon, and has a pressure swinging method (the henceforth, PSA method) absorbs and desorbs using pressure difference and a thermal swinging method (the henceforth, TSA method) absorbs and desorbs using a difference in temperature. Since the PSA method is the method of separating and adsorbing only carbon dioxide by pressurizing and desorbing and recovering by decompressing the carbon dioxide utilizing the principle that the amount of adsorption of carbon dioxide depends on pressure, a pressure vessel is required for it. Precision instruments such as an electromagnetic valve, a compressor, a vacuum pump, etc., are also needed as peripheral equipment, and there is a problem that its enlargement is difficult.
The TSA method is the method of absorbing carbon dioxide at the temperature below Centigrade 50° C. (let all temperature be “Centigrade” henceforth) and desorbing the carbon dioxide by heating in temperature of around 100-200° C. for collecting the carbon dioxide. In the multiple bed type which changes by turns a plurality of adsorption towers filled up with carbon dioxide adsorption material to adsorption and reproduction, there is a fault that a fluctuation of the pressure and concentration of the gas by the change of the towers is not avoided since the pressure loss of gas is high. Also, there is a problem that the enlargement is difficult
Also, in the TSA method, the possible method of formation of a low-pressure power loss or the enlargement by using a rotated type adsorption honeycomb rotor is disclosed in the patent documents 1-5. However, it is insufficient in respect of the energy-saving nature of the recovery rate of carbon dioxide, the concentration of carbon dioxide and the recovery energy.